System for automatically controlling railway traffic



SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC /N VEN TOR yATTORNEY Oct. l, 1,929. w, K, HowE 1,730,323 i SYSTEM Fon VAufrommlCALMcoNTRoLLms RAILWAY TRAFFIC Filed July e, 1915 15 'sheetsfsneet `20.21.1, 1929. W, K, HQWE 1,730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFI f Filed July e, 191515 sheets-Sheet. 5

FIG. 3.

33 .33 FIG- 4.

I By ANU/VIEW `Oct. 1, 1929. w. K. HowE 1,730,323

I SYSTEM FOR AUTOMATICAPLY CONTROLLING RAILWAY TRAFFIC Filed July 6,-1515 15 Sheets-Sheet 4 l l/Vl/ENTR By v Afrik/vn oct. 1, 1929. w. .HQWE1,730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAYv TRAFFIC Filed July 6, 191515 Sheets-Sheet 5v I 8 Ha.

llilllllm V w. K. Hows: 1,730,323 SYSTEM FOR AUTOMATICALLY CONTRLLINGRAILWAY TRAFFIC Oct. l, 192.9.

15 Sheets-Sheet 6 Filed July 1915 p S. WN m TS NS Sw www N l. o `d l Il.nu lllli w l l mrm@ w@ l I www NQ |||||1 www l m o w il @N $2 m.. u -of EHI. Il v l I m ,o l u L l QQ. V H L fl ma m R S* SQ .wm n@ .Q AI

Cet. 1, 1929.

W. K. HOWE 4SYSTEM FOR AUTOMATICALLY GONTOLLING RILWAY TRAFFIC FiledJuly 6, 1915 15 Sheets-Sheet "7A ct. 1, 192.9.' w, K. HOW 1,730,323

UTOMATIGALLY CONTROLLING lRAILWAY TRAFFIC oct. 1, 1929. WK. HowE1,730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC Filed July 6, 191515 sheets-sheet va ,A HG. 12.

0t.1,1929. w. KyHowE 1,730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC oct. 1, 1929.

W. K. HOWE SYSTEM Fon AuToMATlcALLY coNTRoLLING RAILWAY TRAFFIC Filed Juv 6, 41915 15 sheets-sheet 11 RNEV BY A( MAM f,

*y Ao Joa. 1, 1929. w. k. HowE 1,730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC Filed July e, 191515 sheets-sheet 12 W ww bv @n hm. L v

-. Q E mk QS A. 7% v l 4 m2 l l Im J l l I .l I L. f IMJ 1| L .||I l IITal l, w

Oct. l, 1929.

jw. K. HowE 1,730,323

`SYSTEM FR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC Filed July 6, 191515 Sheets-Sheet l5 Gam .ifa/fer @W1K #We a ff TMR/VIEW W. K. HOWE Oct.1, 1929.

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC Filed July 6,'191515 Sheets-Sheet 14 .NNE

IKMN.

w. K. Howr; l730,323

SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAY TRAFFIC Oct. l, 1929.

Fled July 6, 1915 l5 Sheets-Sheet l5 Sw SM Sw RN /Nf/En/ro ATTORNEYPatented Uct. l, 1929 j ige WINTHROP K. HOWE, OF ROCHESTER, NEW YORK,ASSIGNOR TO GENERALRALWAY SIGNAL COIYIPANY, 0F GATES, NEW' YORK, ACORPORATION OF NEW YORK SYSTEM FOR AUTOMATICALLY CONTROLLING RAILWAYTRAFFIC Application filed July 6, 1915. Serial No. 35,132.

This invention relates to systems for controlling railway trallic, andmore particularly to such'systems which will automatically give signalsaboard a car. or train while it is in motion, and which will, ifnecessary, automatically control the speed of the train to conform tothe speed required by the traffic conditions ahead of the train.

At the present time it is possible to construct fiXed signals, that is,signals permanently located along the trackway, which Will respond withpracticable accuracy to changes in traffic conditions; but while it ispossible to set the proper signals for the engineeror the motorman, thisalone does not assure that he will obey the signals, and in many casesserious accidents have been caused by the failure of the engineer toobey these Xed signals. rlhe engineer may fail to see the signals,because fog, snow or other conditions obscure his sight of the signal;or he may see the signal and accidentally or carelessly fail tounderstand the character of the indication which it gives; or' he may beincapacitated for some reason so as to be unable to see, understand, orobey the signal set for him. In any event, regardless of the efficiencyVof the signal system, the safety of the train in the fina-l analysis isdependent on the engineer or motorman; and records show that the humanmachine has an appreciable percentage of failure. To obviate as far aspossible, one source of error it is desirable to provide apparatus,appliances or means of 'some character whereby appropriate signals maybe displayed or operated aboard the'train so that the engineer ormotorman cannot fail to see them; and it is also desirable to supplementthe vigilance and reliability of the engineer or 1notorman by providingappropriate apparatus, appliances or means whereby the speed of thetrain will be automatically controlled in accordance with the conditionsof traiiic ahead of the train in case the engineer himself fails tocontrol the speed of the train.

Various devices have been proposed for accomplishing either or both ofthe above mentioned objects and to obtain 'a clear un-v derstanding ofthe operation and usefulness tem which, it is believed, will add to thesafety of railway traffic and which ,are necessary to secure apracticable system.

Generally stated, the fundamental prin-.

ciple of .governing railway traffic consists in maintaining a certainspace or distance between trains; and inthe well-known block system ofcontrolling lrailway traffic, to which system the system of automaticspeed control embodying this invention is particularlv applicable, thetrackway is divided into blocks or sections and suitable fixed signalsare provided for thefpurpose of keeping a certain number of blocksbetween trains. In this block system, as will be understood by thoseskilled in the art of railway signaling, these fixed signals arecontrolled by track circuits or other devices so that 4the system`operates to display danger or stop signals at diiiierent points alongthe trackwaybehind a train, these stop signals indicating a point beyondwhich the following train should not proceed, at least without greatcare and at a low speed. Also, since itrrequires some distance to reducethe speed. of Y v a fastr moving train, itis desirable -to warn theoperator by a caution signalv when the train is at some distance from astop signal, so that the operator'may apply the brakes in time to bringhis train to a stop before the stop signal is reached, and it is commonpractice to provide such warning signals in the block system ofsignaling.

' The block system affords adequate protection by maintaining aproperintervalof dis-y tance between two trains, vproviding the caution andstop signals are strictly obeyed. rIhe characteristic 0f this blocksystem and of all automatic cab signaling 'and automatic stop systemswhich are intended merely to obtain obedience to the signals of thisblock system,` is that the train is controlled at certain fixed pointsin its travel regardless of its speed at or between these points. Thespeed of the train is, however, a very important factor in regulatingthe spacing of the trains, since the different trains passing over arailway may not, and generally do not, travel atthe same speeds, andalso because dangerous curves, stops at stations, and other fixedhazards prevent the same train from maintaining the same speedthroughout the length of the railway. Primarily, the purpose of anysystem for controlling railway traliic is to obtain safety, and havingsafety the object is to get the greatest capacity for that railway, thatis, the best facility for the movement of vehicles along that railway,and a practicable speed control system should be able to obtain as greata capacity as safety, cost of installation and other conditions willpermit. Without entering into any extended discussionV of the .factorsaffecting the maximum capacity of a railway, it is obvious that superiorcapacity may be obtained if the distance between the trains is reduced,for the reason that the closer the trains are together the more of themmay pass by aparticular point along the railway in a given time. Thiscloser spacing of the trains may be accomplished in the block system byusing short blocks and byspacing the fixed signals controlling theentrance of trains into these blocks closer together; but there is alimitation on the minimum length of a block, since in no case can asignal be closer to a point of danger than a distance amply sufficientto allow the train lto be brought to a stop by its brakes before thepoint of'danger is reached. The distance required to bring a train to astop, or to a speed low enough to make the damage from a collisionslight, depends, as is well known to those skilled in the art of brakingtrains upon a number of things, principally upon the speed at which thetrain is traveling at the time and the grade over which the train istraveling, assuming a particular' kind of braking equipment is used ineach case. Because of this variable braking distance at different speedsand on different grades, a slow moving train at the same part of arailway having the same grade can approach closer to they rear end ofanother train or a point of danger than a fast moving train; and also,when a train is traveling at the same speed, it cannotapproach as closeto the rear end of another train or a point of danger when it istraveling down a steep down grade as it ycan when traveling on the levelor on an upgrade. By proper location and spacing of the fixed signals ofa block system it is possible to make allowance for the variation in thebraking distance due to the grades and other factors which are dependenton the physical condition of the trackway; but, since these signals mustbe spaced so as to protect the fastest and heaviest train running on therailway, no proper allowance is made by the fixed signals for thevarying speed of the different trains, as for instance a fast expresstrain and a slow moving freight train, with the result that the slowertra-ins will be spaced apart by the signals a greater distance than isnecessary for safety, and a corresponding reduction in capacity results.Also, under some conditions it is desirable to permit a train, even ifit is capable of running at a higher speed, to reduce its speed andapproach closer to a train ahead of it. For instance, assuming twotrains at a certain distance apart are'approaching a station or a partof the railway which on account ofcurves or other dangers must betraversed at a slow speed, then as the first train reduces its speed andtakes more'time to move a cert-ain distance, the following train shouldbe able to approach closer to the first train, providing it reduces itsspeed correspondingly, so that after both trains have passed the stationor dangerous part of the railway the distance between them will besubstantially the same as it was before the first train reduced itsspeed. This ideal condition of spacing trains at different parts of therailway according to the kind of train, its braking capacity, its speedand the physical characteristics of that part of the railway which isone of the things which serve to increase capacity, cannot always beobtained; but the speed control system embodying this invention is ofgreat assistance in obtaining a maximum capacity, as will be madeclearer during the .progress of the description.

Also, it is desirable that ra speed control syste-m should be soarrangedand constructed that a train, once it has been placed under thedominance of the speed control system should continuously remain underthis dominance unt-il traffic conditions have become safe. For example,the speed of the train may be properly controlled with reference to onepoint in its travel, but this control at one point does not give anyassurance that the speed will not be greatly increased after that pointhas been passed, thereby resulting in a dangerous condition; nor doesthis control ofv the speed at one fixed point afford proper facility forthe movement of the train since the train may pass this point at acomparatively high Speed and yet by the proper' application of thebrakes its speed may be reduced to a point of safety before the dangerpoint or hazard is reached. f

v From these conditions it is clear that a practicable and efficientspeed apparatus which will permit proper facility for the safe movementof trains along the railway should not only operate to give a warningsignal in the operators cab at a proper distance from reach pointofdanger, and in addition automatically cause the speed of the train to bereduced in case the operator himself does not control the speed inobedience to this warning signal; but also should make due allowance forthe fact that this distance from the point of danger at which thewarning signal 'should be given, and at which the bralres should beapplied will vary, 'being dependent upon the class of the-train anditskind of braking equipment, the speed of the train at the time, the gradeof the track over which the train is traveling, and other. factors,

changing the braking distance of the train.

The speed of a railway train is individual to that train and will varywidely at different points along the railway, so that its speed cannotbe properly regulated solely-with reference to lixed points; but :thespeed control syst-em must be constructed so as to be dependent at eachpointr in the travel of the train upon the speed at which the train istraveling at that point; or, in other words, the Vspeed control systemmust be dependentupoiithe instantaneous actual speed of train. Thegrades and other i'actors which change the braking distance of the trainwill be diiierent at different points along therailway, but will be thesaine in the effect they produce'for every train, so that the speedcontrol system should be responsive to the local conditions orindividual physical characteristics of each part of the trackway.

There are other things to be considered in determining the requisites ofan ehticient and practicable speed control systemV which will aid inobtaining the greatest capacity :tor the movement of trains, and undersome conditions some requisites may be more important than under otherconditions, and consequently, the above discussion should not beunderstood to be comprehensive or invariable but merely illustrative forthe purpose `of obtaining a clearer understanding of the invention.

With the above mentioned and other requisites necessary for apracticable automatic speed control system for railway vehicles in view,one of the principal objects oi' this invention is to devise a systemfor controlling railway vehicles which willA facilitate thel movement ofvehicles by allowing saidvehicles to Aapproach each other as closely assafety will permit.

A further object of the invention is to devise a system for controllingrailway vehicles, in which the speed ot the vehicle and the distance ofsaid vehicle from a point ot danger will be autcmaticallyv involved indetermining the operation of said system.

A further object of the inventionis to devise a system forcontrollingrailway vehicles in which the speed of the vehicle, the

v distance of said vehicle from the point of danger, and the physicalcharacteristicsof'the traclway over which the vehicleis then passingwill be automatically involved in determining the'operation of thesystem.

A further object of the invention 4'is to devise a system forcontrolling railway vehicles which will give asuitable warning, signalaboard the vehicle at anyu point in its travel, said warning signalbeing given at the proper point in the travel of said vehicle so thatthe vehicle will be .safely controlled but will not be unnecessarilydelayed if-its speed is controlled in response to this signal.

A i'urther object of the invention is to devise a system forautomatically controlling railway vehicles which will give an operatorof the vehicle a proper warning signal at any point in its travel, andwhich will, if the speed of the vehicle is not controlled by theoperator in obedience to this warning signal, automatically reduce thespeed of the vehicle, said warning signal and said automatic reductionof speed taking place at a proper pointin the travel of said vehicle sothat the vehicle will be safely controlled but will notbc unnecessarilydelayed.

A further object of the invention is to construct a system forautomatically controlling railwayvehicles which can be-used t regulatethe speed of the vehicle as it travels along the trackwayI accordingtothe special requiren'ients of speed demanded by the fixed hazards atthe different points along the traclrway over which the vehicle ispassing.

fr further object of the invention is to construct 'and arrange theparts of an automatic speed control system so that, in controlling thespeed of the train, due compensation will be made for suoli localconditions along the traclgway as affect the distance in whichthevehicle can be brought to a stop by its brakes.

A further object of the invention is to construct and arrange the partsof an automatic cab-signalling and-speed control system so lthat morethan one vehicle equipped with this 'system may be used in the train,and so that, when more than one such vehicle is used, the systems ofthese vehicles will not interfere with each other in their operation.l

A further object of the invention is to construct andarrange the partsof an automatic cab-signaling and speed `control system so that adequateprotection is'atforded against failure of the important parts Vtooperate properly, and so that such failure, it it'occurs, will beimmediately manifested.

A still 'further object of the invention is to vprovide a suitabledevice for cutting out of service a speed control system on a vehicle,in case this particular speed control systemis out of order, and toconstruct and arrange the parts of this cut-out device so that itsoperation requires certain manipulations which make it ditlicult tocarelessly cut a Vspeed control system out of service.

Other objects and advantages willappear as the description of theinvention progresses,and the novel features of the invention will beparticularly pointed outin the appended claims.

ico

- of the vehicle,

subject to bodying Generally stated, the invention consists in a systemfor controlling railway vehicles, in which appropriate apparatus iscarried on a moving vehicle, which apparatus is controlled at differentpoints along the trackway by suitable devices in accordance with v thetraffic conditions along said trackway and the physical characteristicsof the different parts of said trackway, said apparatus operating sothat, as the vehicle reaches the point where the combined condition ofthe speed its distance from the point of danger and other factorsaffecting the brak` ing distance of the vehicle are such that the brakesshould be applied, the engineer will be advised of this fact by suitablesignals, and if these signals are disregarded the speed of the vehiclewill be automatically reduced.

The invention further consists in the parts, and in the arrangements andcombinations of parts, which will be set forth more fully hereinafter.

The speed control apparatus herein disclosed comprises cooperatingdevices on the vehicle and along the trackway to control the speedapparatus by means of certain electric circuits; a suitable device whichis operated in accordance with the speed at whichthe vehicle istraveling; a device which is operated in accordance with the distancetraveled by the vehicle from a predeterminedv point where saiddevice-wasset into operation; a number of suitable cams, records, registeringdevices, or other instrumentalities having characteristic shapes, eachblock having a cam or the like conforming substantially to theindividual characteristics of said block as regards the factors whichaffect the braking distance of the train; a selector actuated in anyappropriate manner as the train moves along the trackway, which selectorselects the cam or the like conforming nearest to the characteristics 1of the particular block or blocks into which the train will nextproceed; and a system of electric circuits and other inter-connectedapparatus which is the joint action of the device responding tovariations in speed, the device responding to variations in distancetraveled by the vehicle, and the particular cam or the like selected,and which will cause signals to be displayed ory sounded, and which, ifthe signals are not obeyed, will automatically control the speed of thetrain by applying the brakes.

In describing the'invention in detail, reference is had to theaccompanying drawing, wherein is illustrated a preferred physicalembodiment of the invention, and wherein like characters of referencedesignate corresponding parts throughout the several views, and inwhich: Y

Figure 1 is a side elevation of a railway car equipped with speedcontrol apparatus emthe invention, parts of said car being broken away;2 is a diagrammatic plan view showing the arrangement of the parts'ofthe speed control apparatus on the car, parts of said car being brokenaway; Fig. 3 is an enlarged vertical transverse section near one end ofa car equipped with the speed control apparatus and shows the ar#rangement and mounting of some of the parts of said speed controlapparatus; Fig. 4 is a fragmentary enlarged side elevation of part of acar truck showing the manner of mounting thereon the contact shoe whichconstitutes a part of the speed control apparatus; Fig. 5 is an enlargedplan view of the contact shoe detached from the car, the cover for thecasing of said shoe being removed; Fig. 6 is an enlarged verticallongitudinal section of the contact shoe, parts being shown in elevationfor the sake of horizontal section on theline 7--7 in Fig. 6; Fig. 8 isa diagrammatic perspective view showing the operative parts whichconstitutes a part of the speed control apparatus; Fig. 9 is a top planview of the parts of the speed control apparatus which are mounted incasings, hereinafter termed -the gear box and the cam box, the covers ofsaid casings being removed; Fig. 10, is an enlarged verticallongitudinal section through the gear box and the cam box on the line10-10 in Fig. 9 the speed indicator being removed; Fig. 11 is anenlarged vertical transverse section through the gear box substantiallyon the line 11-11 in Fig. 9, parts of said section being separated forthe sake of clearness and the speed indicator being shown as partlyturned; Fig. 12 is a top plan view of one of the units mounted in thecam box and hereinafter termed a block combination, together with itsassociated parts; Fig. 13 is an enlarged vertical transverse sectionthrough the cam box on the line 13--13 in Fig. 9 and shows a blockcombination and its associated parts in elevation; Fig. 14 is anenlarged vertical transverse section through the cam box taken on theline 14-14 in Fig. 9 and showing the multiplier combination inelevation; Fig. 15 is an enlarged fragmentary top plan view of themultiplier arm and its associated gears; Fig. 16 is a fragmentaryvertical section on the line 16-16 in 12; Fig. 17 is a vertical sectionon the line 17-17 in Fig. 9; Fig. 18 is an enlarged fragmentary viewshowing the cam starter arm and its associated gears in elevation; Fig.19 is a horizontal sect-ion through the speed indicator on the line19-19 in Fig. 20; Fig. 2() is a vertical section through the speedindicator taken on the line 20-2() in Fig. 19; Fig. 21 is a diagrammaticview showing the wiring and electrical connections between the parts ofthe speed control system which are mounted on the car; Fig. 22 is adiagrammatic view showing the electrical connections between the partsof the speed control system which of the selector the wheels as shown inFig. `3,

PIT

are located along the traekway; Fig. 23 is a diagrammatic View showingthe electrical connections for the contact shoe; Fig. 24 is an enlargedvertical section through the valve casing of the electrically operatedvalve shown in Fig. 25; Fig. 25 is a vertical diametrical sectionthrough an electrically operated valve suitable for use as a part of thespeed control apparatus for causing lan emergency application of thebrakes, and Fig. 26 is a diagrammatic view illustrating, according tothe well known'method of plotting curves, certain factors and variablequantities with which the speed control apparatus has to deal, said Fig.26 being drawn onk the basis of certain assumed conditions.

Referring to the accompanying drawings, a system for controlling railwaytraiiic embodying the invention is shown applied to an electricallypropelled car of the type commonly used in subways oron elevatedrailways, but it is to be understood that both the invention and theparticular physical einbodnnent shown .are not' limited in theirapplication to this particular' kind of vehicle and are as applicable tosteam locomotives or other railway tractive apparatus as the par- 'Siseat, as shown in Fig. 1.

ticular kind of car shown. The car shown is arranged to be operated ineither direction from a compartment or cab at either end. Thearrangement of the parts of the speed controlling apparatus on the caris shown in the Figs. 1,2, 3 and4. The contact slices B are carried bythe car, and are preferably secured to yokes 37 secured in any suitableway to the trucks k5 of the car, at each end and on opposite sides ofthe car. rlhe selector SR is'also carried by the car, and ispreferablysecured to one of the trucks 5 between the operating pai'ts of saidselector SR being enclosed in a suitable casing. lThe other parts ofthespeed control apparatus, including the speed indicating device Sl, itsassociated gearing and s the cani mechanism, are located in metallic(Fig. 3), which are supported in some accessible place, being preferablymounted on cushioning springs 8, and secured to the frame of vthe carunderneath a These casings 6 and 7 arejoined together so as to be ineffect one casing having' a partition wall extending transverselythereof (Fig. '9) ,but for convenience in description the respectivecasings casings 6 'and 7 willbe hereinafter termed the gear-box 6 andthe cam box 7. j

On one of the axles of the car is mounted a gear casing' 9, (Figs. 1 and3) in which is contained suitable gearing which operatively connectssaid axle with a shaft 10 3) through an intermediate universal coupling11. Telescoping'over the shaft '10 is a tubular shaft'12 having alongitudinal slot therein through which passes a pin 13 fixed to theshaft .10, thereby permitting Vsaid ltubular shaft 12 and said shaft 10to slide longitu* dinally relatively .to .each other, but coinpellingsaid tubular shaft and said shaft 110 to turn together. The tubular-shaft -1-2 connected b v a universal coupling 14 to va vertical shaft15 leading to the speed indicatiing device SI in the gearbox 6. The pinV'and slot connection between kthetubular shaft 12 and shaft 10 and theuniversal couplings 11 and 13 permit the 4parts ofthe apparatus securedto the car body to -followthe usual movements of said car bodyrelatively to the truck 5 without binding the parts or interfering withtheir operation. i

Near one end of the gear box6 and the cam box 7 is a junction box 16which is connected to the cam box 7 by a conduit 17. Each of the contactshoes VB is connectedby a length'of flexible conduit 18 to a length ofrigid conduit 19 bent into an angle and extendingto a point near thepivot axis of the truck;I and connected tothe rigid conduit 19 byv aloopof flexible conduit 2O vis-another-length of rigid conduit 21 whichleadsto vthe junction box 16. The selector SR is also'connected to'the'junction box 16 by lengths of rigid conduit .23 and 25 and flexibleconduit 22 and-24 in the same way as the shoes'B. Near the middle of thecar and at one edgeof the floor thereof, is supported a casing`26 (Figs.1 an'd2) in which are a valve EB (shown' in Figs. 24 and 25) forcontrolling the emergency applicaf tion of the lbrakes of the car, adevice for cutting the speed control appartus on the car out of service,a device P for shutting off power to the car and a valveSB forcontrolling the service application'of the brakes; andrthis casing 26 isconnected to the :junction box 16 by a'conduit 27".` The caris shown asprovided with pneumaticlbrakesof well known construction, 'this systemof brakes comprising a train pipe 28, brake cylinders and auxiliaryreservoirs' 29, suitable automatic controlling valves 30, and lengths offlexible hose 31, by means of which two or more cars can be connected sothat the brakes will be applied simultaneously on all of the cars of thetrainv by venting the train pipe 28. In each cab or compartment for theinotorinan is placed a signal panel,*preferably in the forinvof a casing32 (Fig. 2) adapted to contain lights, movable indicating partev or thelike; and these panels are connected by conduits 33 to the junction box16. yThe junction box. 16 is connected by a conduit 34 to a car junctionbox 35 which is usually provided'ron elec'- trically propelled cars, andan arrangement of conduitsandcouplers, not shown, is made wherebysuitable continuous conductors or busses running the full length yof'the train are provided. 2`

The electrical connections betweenthe different pa'rts ofthe speed'control apparatus are not shown in the gures illustrating theconstruction offthese parts inorderfto 'avoid

